The U.S. Transportation Department is looking into complaints from some Toyota owners who say they are still experiencing problems with unintended acceleration even after repairs to their recalled vehicles. The complaints raise concerns that safety issues that led to the recall of more than eight million vehicles may not be mechanical in nature, as Toyota engineers claim.

February 24 in Washington, U.S. lawmakers heard words of assurance from top Toyota officials.

"Toyota engineers have developed effective and durable solutions for the vehicles we have recalled," said one.

But Toyota owner Stewart Stogel is not so sure.

"Whatever they did, didn't' work," said Stewart Stogel.

Stogel says he picked up his recalled 2009 Camry from a dealer after getting repairs to fix a sticky gas pedal. He says what happened next came as a big surprise.

"I almost got into a serious accident after the fix was done," he said. "I was saved only by a few feet and about a second going down an embankment and smashing into a brick wall."

Stogel took his car back to the dealer, but he says the service manager was unable to give him answers.

'We're going to have to look at the car," said the service manager. "I have Toyota on standby to help us with our investigation, and we definitely want to get to the bottom of it."

So does the National Highway Traffic Safety Administration (NHTSA). The agency has received at least 10 similar complaints and wants to hear from other owners who have experienced problems after repairs were done.

Safety experts say the new complaints underscore the need for tougher safety standards.Clarence Ditlow at the Center for Auto Safety in Washington says the problem may be caused by faulty electronics.

"Today's modern car is in a way more sophisticated than a fighter jet in terms of the computers that are in it but we don't have any reassurance as to what standards went into designing the computer software that goes into those vehicles," said Clarence Ditlow.

NHTSA says the Toyota recalls are linked to at least 50 accidental deaths.U.S. lawmakers are expected to push for new tests and new regulations after holding a series of hearings last week on auto safety.